// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// +build !nopsshandshake
package pss
import (
"context"
"errors"
"fmt"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/rpc"
"github.com/ethereum/go-ethereum/swarm/log"
)
const (
IsActiveHandshake = true
)
var (
ctrlSingleton *HandshakeController
)
const (
defaultSymKeyRequestTimeout = 1000 * 8 // max wait ms to receive a response to a handshake symkey request
defaultSymKeyExpiryTimeout = 1000 * 10 // ms to wait before allowing garbage collection of an expired symkey
defaultSymKeySendLimit = 256 // amount of messages a symkey is valid for
defaultSymKeyCapacity = 4 // max number of symkeys to store/send simultaneously
)
// symmetric key exchange message payload
type handshakeMsg struct {
From []byte
Limit uint16
Keys [][]byte
Request uint8
Topic Topic
}
// internal representation of an individual symmetric key
type handshakeKey struct {
symKeyID *string
pubKeyID *string
limit uint16
count uint16
expiredAt time.Time
}
// container for all in- and outgoing keys
// for one particular peer (public key) and topic
type handshake struct {
outKeys []handshakeKey
inKeys []handshakeKey
}
// Initialization parameters for the HandshakeController
//
// SymKeyRequestExpiry: Timeout for waiting for a handshake reply
// (default 8000 ms)
//
// SymKeySendLimit: Amount of messages symmetric keys issues by
// this node is valid for (default 256)
//
// SymKeyCapacity: Ideal (and maximum) amount of symmetric keys
// held per direction per peer (default 4)
type HandshakeParams struct {
SymKeyRequestTimeout time.Duration
SymKeyExpiryTimeout time.Duration
SymKeySendLimit uint16
SymKeyCapacity uint8
}
// Sane defaults for HandshakeController initialization
func NewHandshakeParams() *HandshakeParams {
return &HandshakeParams{
SymKeyRequestTimeout: defaultSymKeyRequestTimeout * time.Millisecond,
SymKeyExpiryTimeout: defaultSymKeyExpiryTimeout * time.Millisecond,
SymKeySendLimit: defaultSymKeySendLimit,
SymKeyCapacity: defaultSymKeyCapacity,
}
}
// Singleton object enabling semi-automatic Diffie-Hellman
// exchange of ephemeral symmetric keys
type HandshakeController struct {
pss *Pss
keyC map[string]chan []string // adds a channel to report when a handshake succeeds
lock sync.Mutex
symKeyRequestTimeout time.Duration
symKeyExpiryTimeout time.Duration
symKeySendLimit uint16
symKeyCapacity uint8
symKeyIndex map[string]*handshakeKey
handshakes map[string]map[Topic]*handshake
deregisterFuncs map[Topic]func()
}
// Attach HandshakeController to pss node
//
// Must be called before starting the pss node service
func SetHandshakeController(pss *Pss, params *HandshakeParams) error {
ctrl := &HandshakeController{
pss: pss,
keyC: make(map[string]chan []string),
symKeyRequestTimeout: params.SymKeyRequestTimeout,
symKeyExpiryTimeout: params.SymKeyExpiryTimeout,
symKeySendLimit: params.SymKeySendLimit,
symKeyCapacity: params.SymKeyCapacity,
symKeyIndex: make(map[string]*handshakeKey),
handshakes: make(map[string]map[Topic]*handshake),
deregisterFuncs: make(map[Topic]func()),
}
api := &HandshakeAPI{
namespace: "pss",
ctrl: ctrl,
}
pss.addAPI(rpc.API{
Namespace: api.namespace,
Version: "0.2",
Service: api,
Public: true,
})
ctrlSingleton = ctrl
return nil
}
// Return all unexpired symmetric keys from store by
// peer (public key), topic and specified direction
func (ctl *HandshakeController) validKeys(pubkeyid string, topic *Topic, in bool) (validkeys []*string) {
ctl.lock.Lock()
defer ctl.lock.Unlock()
now := time.Now()
if _, ok := ctl.handshakes[pubkeyid]; !ok {
return []*string{}
} else if _, ok := ctl.handshakes[pubkeyid][*topic]; !ok {
return []*string{}
}
var keystore *[]handshakeKey
if in {
keystore = &(ctl.handshakes[pubkeyid][*topic].inKeys)
} else {
keystore = &(ctl.handshakes[pubkeyid][*topic].outKeys)
}
for _, key := range *keystore {
if key.limit <= key.count {
ctl.releaseKey(*key.symKeyID, topic)
} else if !key.expiredAt.IsZero() && key.expiredAt.Before(now) {
ctl.releaseKey(*key.symKeyID, topic)
} else {
validkeys = append(validkeys, key.symKeyID)
}
}
return
}
// Add all given symmetric keys with validity limits to store by
// peer (public key), topic and specified direction
func (ctl *HandshakeController) updateKeys(pubkeyid string, topic *Topic, in bool, symkeyids []string, limit uint16) {
ctl.lock.Lock()
defer ctl.lock.Unlock()
if _, ok := ctl.handshakes[pubkeyid]; !ok {
ctl.handshakes[pubkeyid] = make(map[Topic]*handshake)
}
if ctl.handshakes[pubkeyid][*topic] == nil {
ctl.handshakes[pubkeyid][*topic] = &handshake{}
}
var keystore *[]handshakeKey
expire := time.Now()
if in {
keystore = &(ctl.handshakes[pubkeyid][*topic].inKeys)
} else {
keystore = &(ctl.handshakes[pubkeyid][*topic].outKeys)
expire = expire.Add(time.Millisecond * ctl.symKeyExpiryTimeout)
}
for _, storekey := range *keystore {
storekey.expiredAt = expire
}
for i := 0; i < len(symkeyids); i++ {
storekey := handshakeKey{
symKeyID: &symkeyids[i],
pubKeyID: &pubkeyid,
limit: limit,
}
*keystore = append(*keystore, storekey)
ctl.pss.symKeyPool[*storekey.symKeyID][*topic].protected = true
}
for i := 0; i < len(*keystore); i++ {
ctl.symKeyIndex[*(*keystore)[i].symKeyID] = &((*keystore)[i])
}
}
// Expire a symmetric key, making it elegible for garbage collection
func (ctl *HandshakeController) releaseKey(symkeyid string, topic *Topic) bool {
if ctl.symKeyIndex[symkeyid] == nil {
log.Debug("no symkey", "symkeyid", symkeyid)
return false
}
ctl.symKeyIndex[symkeyid].expiredAt = time.Now()
log.Debug("handshake release", "symkeyid", symkeyid)
return true
}
// Checks all symmetric keys in given direction(s) by
// specified peer (public key) and topic for expiry.
// Expired means:
// - expiry timestamp is set, and grace period is exceeded
// - message validity limit is reached
func (ctl *HandshakeController) cleanHandshake(pubkeyid string, topic *Topic, in bool, out bool) int {
ctl.lock.Lock()
defer ctl.lock.Unlock()
var deletecount int
var deletes []string
now := time.Now()
handshake := ctl.handshakes[pubkeyid][*topic]
log.Debug("handshake clean", "pubkey", pubkeyid, "topic", topic)
if in {
for i, key := range handshake.inKeys {
if key.expiredAt.Before(now) || (key.expiredAt.IsZero() && key.limit <= key.count) {
log.Trace("handshake in clean remove", "symkeyid", *key.symKeyID)
deletes = append(deletes, *key.symKeyID)
handshake.inKeys[deletecount] = handshake.inKeys[i]
deletecount++
}
}
handshake.inKeys = handshake.inKeys[:len(handshake.inKeys)-deletecount]
}
if out {
deletecount = 0
for i, key := range handshake.outKeys {
if key.expiredAt.Before(now) && (key.expiredAt.IsZero() && key.limit <= key.count) {
log.Trace("handshake out clean remove", "symkeyid", *key.symKeyID)
deletes = append(deletes, *key.symKeyID)
handshake.outKeys[deletecount] = handshake.outKeys[i]
deletecount++
}
}
handshake.outKeys = handshake.outKeys[:len(handshake.outKeys)-deletecount]
}
for _, keyid := range deletes {
delete(ctl.symKeyIndex, keyid)
ctl.pss.symKeyPool[keyid][*topic].protected = false
}
return len(deletes)
}
// Runs cleanHandshake() on all peers and topics
func (ctl *HandshakeController) clean() {
peerpubkeys := ctl.handshakes
for pubkeyid, peertopics := range peerpubkeys {
for topic := range peertopics {
ctl.cleanHandshake(pubkeyid, &topic, true, true)
}
}
}
// Passed as a PssMsg handler for the topic handshake is activated on
// Handles incoming key exchange messages and
// ccunts message usage by symmetric key (expiry limit control)
// Only returns error if key handler fails
func (ctl *HandshakeController) handler(msg []byte, p *p2p.Peer, asymmetric bool, symkeyid string) error {
if !asymmetric {
if ctl.symKeyIndex[symkeyid] != nil {
if ctl.symKeyIndex[symkeyid].count >= ctl.symKeyIndex[symkeyid].limit {
return fmt.Errorf("discarding message using expired key: %s", symkeyid)
}
ctl.symKeyIndex[symkeyid].count++
log.Trace("increment symkey recv use", "symsymkeyid", symkeyid, "count", ctl.symKeyIndex[symkeyid].count, "limit", ctl.symKeyIndex[symkeyid].limit, "receiver", common.ToHex(crypto.FromECDSAPub(ctl.pss.PublicKey())))
}
return nil
}
keymsg := &handshakeMsg{}
err := rlp.DecodeBytes(msg, keymsg)
if err == nil {
err := ctl.handleKeys(symkeyid, keymsg)
if err != nil {
log.Error("handlekeys fail", "error", err)
}
return err
}
return nil
}
// Handle incoming key exchange message
// Add keys received from peer to store
// and enerate and send the amount of keys requested by peer
//
// TODO:
// - flood guard
// - keylength check
// - update address hint if:
// 1) leftmost bytes in new address do not match stored
// 2) else, if new address is longer
func (ctl *HandshakeController) handleKeys(pubkeyid string, keymsg *handshakeMsg) error {
// new keys from peer
if len(keymsg.Keys) > 0 {
log.Debug("received handshake keys", "pubkeyid", pubkeyid, "from", keymsg.From, "count", len(keymsg.Keys))
var sendsymkeyids []string
for _, key := range keymsg.Keys {
sendsymkey := make([]byte, len(key))
copy(sendsymkey, key)
var address PssAddress
copy(address[:], keymsg.From)
sendsymkeyid, err := ctl.pss.setSymmetricKey(sendsymkey, keymsg.Topic, &address, false, false)
if err != nil {
return err
}
sendsymkeyids = append(sendsymkeyids, sendsymkeyid)
}
if len(sendsymkeyids) > 0 {
ctl.updateKeys(pubkeyid, &keymsg.Topic, false, sendsymkeyids, keymsg.Limit)
ctl.alertHandshake(pubkeyid, sendsymkeyids)
}
}
// peer request for keys
if keymsg.Request > 0 {
_, err := ctl.sendKey(pubkeyid, &keymsg.Topic, keymsg.Request)
if err != nil {
return err
}
}
return nil
}
// Send key exchange to peer (public key) valid for `topic`
// Will send number of keys specified by `keycount` with
// validity limits specified in `msglimit`
// If number of valid outgoing keys is less than the ideal/max
// amount, a request is sent for the amount of keys to make up
// the difference
func (ctl *HandshakeController) sendKey(pubkeyid string, topic *Topic, keycount uint8) ([]string, error) {
var requestcount uint8
to := &PssAddress{}
if _, ok := ctl.pss.pubKeyPool[pubkeyid]; !ok {
return []string{}, errors.New("Invalid public key")
} else if psp, ok := ctl.pss.pubKeyPool[pubkeyid][*topic]; ok {
to = psp.address
}
recvkeys := make([][]byte, keycount)
recvkeyids := make([]string, keycount)
ctl.lock.Lock()
if _, ok := ctl.handshakes[pubkeyid]; !ok {
ctl.handshakes[pubkeyid] = make(map[Topic]*handshake)
}
ctl.lock.Unlock()
// check if buffer is not full
outkeys := ctl.validKeys(pubkeyid, topic, false)
if len(outkeys) < int(ctl.symKeyCapacity) {
//requestcount = uint8(self.symKeyCapacity - uint8(len(outkeys)))
requestcount = ctl.symKeyCapacity
}
// return if there's nothing to be accomplished
if requestcount == 0 && keycount == 0 {
return []string{}, nil
}
// generate new keys to send
for i := 0; i < len(recvkeyids); i++ {
var err error
recvkeyids[i], err = ctl.pss.GenerateSymmetricKey(*topic, to, true)
if err != nil {
return []string{}, fmt.Errorf("set receive symkey fail (pubkey %x topic %x): %v", pubkeyid, topic, err)
}
recvkeys[i], err = ctl.pss.GetSymmetricKey(recvkeyids[i])
if err != nil {
return []string{}, fmt.Errorf("GET Generated outgoing symkey fail (pubkey %x topic %x): %v", pubkeyid, topic, err)
}
}
ctl.updateKeys(pubkeyid, topic, true, recvkeyids, ctl.symKeySendLimit)
// encode and send the message
recvkeymsg := &handshakeMsg{
From: ctl.pss.BaseAddr(),
Keys: recvkeys,
Request: requestcount,
Limit: ctl.symKeySendLimit,
Topic: *topic,
}
log.Debug("sending our symkeys", "pubkey", pubkeyid, "symkeys", recvkeyids, "limit", ctl.symKeySendLimit, "requestcount", requestcount, "keycount", len(recvkeys))
recvkeybytes, err := rlp.EncodeToBytes(recvkeymsg)
if err != nil {
return []string{}, fmt.Errorf("rlp keymsg encode fail: %v", err)
}
// if the send fails it means this public key is not registered for this particular address AND topic
err = ctl.pss.SendAsym(pubkeyid, *topic, recvkeybytes)
if err != nil {
return []string{}, fmt.Errorf("Send symkey failed: %v", err)
}
return recvkeyids, nil
}
// Enables callback for keys received from a key exchange request
func (ctl *HandshakeController) alertHandshake(pubkeyid string, symkeys []string) chan []string {
if len(symkeys) > 0 {
if _, ok := ctl.keyC[pubkeyid]; ok {
ctl.keyC[pubkeyid] <- symkeys
close(ctl.keyC[pubkeyid])
delete(ctl.keyC, pubkeyid)
}
return nil
}
if _, ok := ctl.keyC[pubkeyid]; !ok {
ctl.keyC[pubkeyid] = make(chan []string)
}
return ctl.keyC[pubkeyid]
}
type HandshakeAPI struct {
namespace string
ctrl *HandshakeController
}
// Initiate a handshake session for a peer (public key) and topic
// combination.
//
// If `sync` is set, the call will block until keys are received from peer,
// or if the handshake request times out
//
// If `flush` is set, the max amount of keys will be sent to the peer
// regardless of how many valid keys that currently exist in the store.
//
// Returns list of symmetric key ids that can be passed to pss.GetSymmetricKey()
// for retrieval of the symmetric key bytes themselves.
//
// Fails if the incoming symmetric key store is already full (and `flush` is false),
// or if the underlying key dispatcher fails
func (api *HandshakeAPI) Handshake(pubkeyid string, topic Topic, sync bool, flush bool) (keys []string, err error) {
var hsc chan []string
var keycount uint8
if flush {
keycount = api.ctrl.symKeyCapacity
} else {
validkeys := api.ctrl.validKeys(pubkeyid, &topic, false)
keycount = api.ctrl.symKeyCapacity - uint8(len(validkeys))
}
if keycount == 0 {
return keys, errors.New("Incoming symmetric key store is already full")
}
if sync {
hsc = api.ctrl.alertHandshake(pubkeyid, []string{})
}
_, err = api.ctrl.sendKey(pubkeyid, &topic, keycount)
if err != nil {
return keys, err
}
if sync {
ctx, cancel := context.WithTimeout(context.Background(), api.ctrl.symKeyRequestTimeout)
defer cancel()
select {
case keys = <-hsc:
log.Trace("sync handshake response receive", "key", keys)
case <-ctx.Done():
return []string{}, errors.New("timeout")
}
}
return keys, nil
}
// Activate handshake functionality on a topic
func (api *HandshakeAPI) AddHandshake(topic Topic) error {
api.ctrl.deregisterFuncs[topic] = api.ctrl.pss.Register(&topic, api.ctrl.handler)
return nil
}
// Deactivate handshake functionality on a topic
func (api *HandshakeAPI) RemoveHandshake(topic *Topic) error {
if _, ok := api.ctrl.deregisterFuncs[*topic]; ok {
api.ctrl.deregisterFuncs[*topic]()
}
return nil
}
// Returns all valid symmetric keys in store per peer (public key)
// and topic.
//
// The `in` and `out` parameters indicate for which direction(s)
// symmetric keys will be returned.
// If both are false, no keys (and no error) will be returned.
func (api *HandshakeAPI) GetHandshakeKeys(pubkeyid string, topic Topic, in bool, out bool) (keys []string, err error) {
if in {
for _, inkey := range api.ctrl.validKeys(pubkeyid, &topic, true) {
keys = append(keys, *inkey)
}
}
if out {
for _, outkey := range api.ctrl.validKeys(pubkeyid, &topic, false) {
keys = append(keys, *outkey)
}
}
return keys, nil
}
// Returns the amount of messages the specified symmetric key
// is still valid for under the handshake scheme
func (api *HandshakeAPI) GetHandshakeKeyCapacity(symkeyid string) (uint16, error) {
storekey := api.ctrl.symKeyIndex[symkeyid]
if storekey == nil {
return 0, fmt.Errorf("invalid symkey id %s", symkeyid)
}
return storekey.limit - storekey.count, nil
}
// Returns the byte representation of the public key in ascii hex
// associated with the given symmetric key
func (api *HandshakeAPI) GetHandshakePublicKey(symkeyid string) (string, error) {
storekey := api.ctrl.symKeyIndex[symkeyid]
if storekey == nil {
return "", fmt.Errorf("invalid symkey id %s", symkeyid)
}
return *storekey.pubKeyID, nil
}
// Manually expire the given symkey
//
// If `flush` is set, garbage collection will be performed before returning.
//
// Returns true on successful removal, false otherwise
func (api *HandshakeAPI) ReleaseHandshakeKey(pubkeyid string, topic Topic, symkeyid string, flush bool) (removed bool, err error) {
removed = api.ctrl.releaseKey(symkeyid, &topic)
if removed && flush {
api.ctrl.cleanHandshake(pubkeyid, &topic, true, true)
}
return
}
// Send symmetric message under the handshake scheme
//
// Overloads the pss.SendSym() API call, adding symmetric key usage count
// for message expiry control
func (api *HandshakeAPI) SendSym(symkeyid string, topic Topic, msg hexutil.Bytes) (err error) {
err = api.ctrl.pss.SendSym(symkeyid, topic, msg[:])
if api.ctrl.symKeyIndex[symkeyid] != nil {
if api.ctrl.symKeyIndex[symkeyid].count >= api.ctrl.symKeyIndex[symkeyid].limit {
return errors.New("attempted send with expired key")
}
api.ctrl.symKeyIndex[symkeyid].count++
log.Trace("increment symkey send use", "symkeyid", symkeyid, "count", api.ctrl.symKeyIndex[symkeyid].count, "limit", api.ctrl.symKeyIndex[symkeyid].limit, "receiver", common.ToHex(crypto.FromECDSAPub(api.ctrl.pss.PublicKey())))
}
return
}
